Overview
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ABSTRACT
Lightning protection of a structure is carried out by a Lightning Protection System comprising an external part (capture, down conductors, lightning earthing system and equipotential bonding) and an internal part (shielding, Surge Protective Device). The protection level, from I to IV, characterizes the effectiveness of the SPF with I being the best level.
Lightning Risk Analysis is the technique used to determine this level of protection. Once the level of protection has been set, it is possible to position the capture devices. The number of down conductors and the earth connection depends on this level of protection, as do Type 1 SPDs which provide equipotentiality between the electrical networks entering the structure and the earthing system.
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Read the articleAUTHOR
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Alain ROUSSEAU: Engineer, École Centrale de Lyon – DEA in Electrical Engineering - Chairman SEFTIM – Chairman of AFNOR and CENELEC Lightning Protection Standardization Committees. Chairman of the IEC Lightning Arrester Standardization Committee - SEFTIM, Vincennes (France)
INTRODUCTION
General design of a lightning protection system
Total protection against lightning is illusory. The risk incurred must therefore be analyzed and controlled, and this is the purpose of an analysis method called LRA (Lightning Risk Analysis). Where protection against direct lightning strikes and the induced effects of lightning current is required, the only solution is to surround the object to be protected with a Faraday cage, unless the object itself is made of conductive metal.
However, the application of the Faraday cage for direct lightning protection, the mesh cage, has an effectiveness that varies according to the size of the mesh and also the height of the mesh in relation to the roof. For protection against induced effects, it is essentially the fact of reducing the current in each conductor by distributing the initial current in the various meshes that brings a beneficial effect.
Although the term "lightning conductor" is often used in everyday language to refer to protection against direct lightning strikes, the lightning conductor is in fact just one of the capture devices. On the other hand, protection against the impact and effects of lightning is not simply a matter of capturing the lightning shock, but must also safely conduct the lightning to ground. The term SPF (lightning protection system) is used to describe this protection.
At the same time, lightning conductors known as PDAs (lightning conductors with an ignition device) are reputed to be more effective than Franklin-type rods (known as PTSs (single rod lightning conductors) as opposed to PDAs).
What has just been said concerns the traditional concept of protection for structures (buildings, edifices, buildings, etc.) whose function is to prevent damage from direct lightning strikes, and which is commonly referred to as an "external protection system".
The generic word used in the standard is "structure", which can refer to a building, an industrial structure (e.g. a hangar) or a civil engineering structure (e.g. a bridge), and can be assimilated to the term "construction". A building is a residential or office structure. A building generally has remarkable architectural properties. A building is any urban structure divided into apartments or converted into offices. Depending on the case, these terms will be used in the text with a similar meaning to "structure". The term "structure" should not be confused with the load-bearing structure, which is only one part of the structure.
Today, however, there's a clear tendency to insist, in parallel, on the need to install an "interior protection system". In fact, electrical and...
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KEYWORDS
risk | lightning rod | lightning | fire protections | collective protection | individual protection
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Lightning and building protection – Protection techniques
General design of a protection system
Bibliography
Standards and norms
AFNOR
- Low-voltage arresters – Part 11: Surge arresters connected to low-voltage systems – Requirements and test methods - NF EN 61643-11/A11 - 2018
- Low-voltage surge arresters – Part 21: Surge arresters connected to signal and telecommunication networks – Operating specifications and test methods - NF EN 61643-21/A2 - 2013
- Protection contre la foudre Partie 1 : Principes généraux...
Regulations
ICPE Order: Arrêté du 11 mai 2015 modifiant une série d'arrêtés ministériels pour prendre en compte la nouvelle nomenclature des installations classées pour la protection de l'environnement entrant en vigueur au 1 er juin 2015 dans le cadre de la transposition de la directive no 2012/18/UE du 4 juillet 2012.
Decree known as INB: Decree of 07/02/12 laying...
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